1. Field of the Invention
The present invention relates to a quick-acting coupling which is employed for quickly connecting or disconnecting halfway portions of a hydraulic line, for example for use in a hydraulic clamp apparatus for fixing a work in a machine tool.
2. Description of the Prior Art
A quick-acting coupling as a subject of the present invention will be explained more concretely hereinafter. The quick-acting coupling is of the type comprising a pair of couplings provided with check valves and non-spill valves (in other words, spill preventive valves) respectively so that a leak of liquid such as a working oil can be prevented by means of the check valves and a spill of liquid can be prevented by means of the non-spill valves when the couplings are disconnected.
Such a quick-acting coupling with the check valves and the non-spill valves on opposite sides for use in liquid is used for preventing products and atmosphere from being contaminated by the liquid because the coupling is adapted to prevent the spill-out of liquid outside the connection ports during the disconnecting manipulation thereof. Its basic construction known by the inventor of the present invention is shown in FIG. 11 for a first conventional embodiment.
In FIG. 11(a), a quick-acting coupling 26' includes a first coupling 51' and a second coupling 52'.
The first coupling 51' is provided with a coupling body 53', a check valve body 54', a non-spill valve body 55', a non-spill valve casing 56', a check valve spring 57', a non-spill valve casing spring 58' and a rod 59'.
The coupling body 53' is provided in its inside with a non-spill valve casing chamber 63' and a check valve chamber 66' in order from the butt connection side JA to the pull-off disconnection side UA. The check valve chamber 66'accommodates the check valve body 54' and the check valve spring 57' therewithin. The non-spill valve casing chamber 63' accommodates the non-spill valve casing 56' therewithin. The non-spill valve body 55' is disposed so as to face the non-spill valve port surface 71' at the leading end of the casing bore 56a' of the non-spill valve casing 56'. The inside of the non-spill valve port surface 71' is in communication to the check valve chamber 66' through the casing bore 56a' of the non-spill valve casing 56', and the non-spill valve body 55' and the check valve body 54' are connected to each other through the rod 59'.
The check valve body 54' is urged toward the butt connection side JA by means of the check valve spring 57'within the check valve chamber 66' so as to be brought into contact with a check valve seat 72' of the check valve chamber 66' for the valve closing. On one hand, the rod 59'transmits the movement of the non-spill valve body 55'toward the pull-off disconnection side UA by an external force to the check valve body 54' so as to shift the check valve body 54' to its valve opening position and on the other hand, it limits the movement of the non-spill valve body 55' toward the butt connection side JA. The non-spill valve casing 56' is adapted to be pushed toward the butt connection side JA by means of the non-spill valve casing spring 58'within the non-spill valve casing chamber 63' so as to bring the non-spill valve port surface 71' into contact with the non-spill valve body 55' for the valve closing.
The second coupling 52' is provided with a coupling body 153', a check valve body 154', a non-spill valve body 155', a check valve spring 157', a non-spill valve spring 158' and a rod 159'.
The coupling body 153' is provided in its inside with a non-spill valve chamber 163' and a check valve chamber 166'in order from a butt connection side JB to a pull-off disconnection side UB, and the non-spill valve chamber 163'is in communication with the check valve chamber 166'. The check valve chamber 166' accommodates the check valve body 154' and the check valve spring 157' therewithin, the non-spill valve chamber 163' accommodates the non-spill valve body 155' therewithin, the non-spill valve body 155' is disposed so as to face a non-spill valve port surface 171'at the leading end of the non-spill valve chamber 163', and the rod 159' is interposed between the non-spill valve body 155' and the check valve body 154'.
The check valve body 154' is urged toward the butt connection side JB by means of the check valve spring 157'within the check valve chamber 166' so as to be brought into contact with a check valve seat 172' of the check valve chamber 166' for the valve closing. The rod 159'transmits the movement of the non-spill valve body 155'toward the pull-off disconnection side UB by an external force to the check valve body 154' so as to shift the check valve body 154' to its valve opening position. On the one hand, the non-spill valve body 155' is adapted to be pushed toward the butt connection side JB by means of the non-spill valve spring 158' within the non-spill valve chamber 163' so as to close the non-spill valve port surface 171' of the non-spill valve chamber 163' and on the other hand, it is adapted to be pushed toward the pull-off disconnection side UB by an external force so as to open the non-spill valve port surface 171'.
In the above-mentioned basic construction, a conventional construction for liquid-tightly sealing the non-spill valve casing chamber 63' and the non-spill valve chamber 163' under the disconnected condition of both the couplings 51', 52'will be explained more in detail hereinafter.
In this prior art, the non-spill valve bodies 55', 155'are of a seat valve type. The first non-spill valve body 55' is adapted to be brought into contact with the tapered non-spill valve port surface 71' from the butt connection side JA to the pull-off disconnection side UA for the valve closing and the second non-spill valve body 155' is adapted to be brought into contact with the tapered non-spill valve port surface 171' from the pull-off disconnection side UB to the butt connection side JB for the valve closing.
The quick-acting coupling 26' for use in liquid having the aforementioned construction operates as follows during the connecting manipulation.
FIG. 11(a) shows the connection starting condition. The respective valve bodies 54', 55', 154', 155' are shifted to the valve closing positions by the springs 57', 58', 157', 158' respectively so as to shut off the communication between both oil supply and discharge ports 62', 162' at the opposite ends. Under this condition, the non-spill valve casing 56' of the first coupling 51' and a valve casing pushing portion 156' of the second coupling 52' are brought into contact with a sealing means 84' for sealing off.
When the first coupling 51' is advanced toward the butt connection side JA on the right side with respect to the second coupling 52', the condition shown in FIG. 11(b) is obtained after the following operations. Firstly, the non-spill valve casing spring 58' is contracted so that the non-spill valve body 55' is separated apart from the non-spill valve port surface 71' and both the valve bodies 55', 155' are butted to each other. Then, the non-spill valve spring 158 is contracted so that the non-spill valve body 155' is separated apart from the non-spill valve port surface 171' and the rod 159' is brought into contact with the check valve body 154'.
Further, as the first coupling 51' is advanced, as shown in FIG. 11(c), firstly the first check valve body 54' is shifted to its valve opening position and then as shown in FIG. 11(d), the second check valve body 154' is shifted to its valve opening position so that both the oil supply and discharge ports 62', 162' are communicated to each other.
On the other hand, the following operations of the quick-acting coupling 26' are carried out during the disconnecting manipulation subsequent to the connection completed condition shown in FIG. 11(d).
When the first coupling 51' is retreated toward the pull-off disconnection side UA on the left side with respect to the second coupling 52', as shown in FIG. 11(c), firstly the second check valve body 154' is shifted to its valve closing position and then as shown in FIG. 11(b), the first check valve body 54' is shifted to its valve closing position. As the first coupling 51' is retreated, the following operations are carried out. That is, as the non-spill valve spring 158' and the non-spill valve casing spring 58' extend, firstly the second rod 159' is separated apart from the check valve body 154' and the second non-spill valve body 155' is brought into contact with the non-spill valve port surface 171' for the valve closing and then the first non-spill valve port surface 71' is brought into contact with the non-spill valve body 55' for the valve closing.
There are, however, following problems associated with the above-mentioned first conventional embodiment.
(a) A spill-out of liquid is caused during the disconnecting manipulation.
Since the quick-acting coupling 26' operates as mentioned above, a time lag can't help being brought about in the valve closing timing of the non-spill valve bodies 55', 155' at the time of disconnecting manipulation of both the couplings 51', 52'.
Further, at the time of connecting manipulation of both the couplings 51', 52', since firstly it is necessary to seal between the non-spill valve casing 56' and the valve casing pushing portion 156' by means of the sealing means 84', a gap can't help being provided between both the butting surfaces of the non-spill valve bodies 55', 155' in order to compensate contact errors between the respective non-spill valve bodies 55', 155' and the respective non-spill valve port surfaces 71', 171'. In other words, just before disconnecting both the couplings 51', 52', a gap is provided between both the butting surfaces of the non-spill valve bodies 55', 155'.
Since there is a time lag in the valve closing timing and there is provided a gap between both the valve bodies in that way, a liquid pool is formed between both the non-spill valve bodies 55', 155' just before their disconnections. Further, the quantity of this liquid pool can't help become larger owing to a gap provided by chamfers formed at the peripheral portions of both the valve bodies 55', 155'. Resultantly, the spill-out of liquid is caused at the time of disconnecting manipulation.
(b) The durability for the spill prevention is low.
Since the non-spill valve bodies 55', 155' of the seat valve type and the non-spill valve port surfaces 71', 171' are apt to be damaged by foreign substances and the like bitten therebetween, the liquid-tight sealing is readily broken. Therefore, the durability for the spill prevention is low.
(c) A large force is required for the connecting manipulation.
Since the non-spill valve bodies 55', 155' are shifted to the valve closing positions with the non-spill valve casing chamber 63' and the non-spill valve chamber 163' being kept under high pressure conditions at the time of disconnecting manipulation of both the couplings 51', 52', a large manipulation force is required for the connecting manipulation at the next time.
Further, has been known another quick-acting coupling having a different basic construction from the above-mentioned first conventional embodiment and provided with a cleaning device of a fluid blow type. This coupling is adapted to remove foreign substances attached to connecting portions of a pair of couplings of a quick-acting coupling by means of the blow employing a cleaning fluid such as a pressure air and the like so as to clean the connecting portions when the pair of couplings is connected.
As such a quick-acting coupling with the cleaning device, has been known the one disclosed in Japanese Provisional Utility Model No. 1985-52496 (referred to as a second conventional embodiment, hereinafter) previously proposed by the inventer of the present invention. This coupling is constructed as follows, as shown in FIG. 12.
A connecting insert portion 161" is formed at the leading end portion of a coupling body 153" of a second coupling 52". A flow passage 160" on a second coupling side is opened in the leading end surface 161a" of the connecting insert portion 161", and an annular sealing contact portion 189" is formed in the connecting insert portion 161" at the central portion in the right and left direction of an outer surrounding surface 161b" thereof 161".
A connecting receive mouth 61" is formed in the leading end portion of a coupling body 53" of a first coupling 51" in a concaved fashion. A flow passage 60" on a first coupling side is opened in the inmost end surface 61a" of the connecting receive mouth 61", and an annular sealing contact portion 89" is provided in the connecting receive mouth 61" at the central portion in the right and left direction of an inner surrounding surface 61b" thereof 61". A plurality of ejection holes 85" are opened in the inner surrounding surface 61b" of the connecting receive mouth 61" at the leading end portion in a forward inclined manner so as to eject a cleaning fluid F. Under the midway condition of the connection between the first coupling 51" and the second coupling 52" as shown in FIG. 12(a), the cleaning fluid F ejected from the ejection holes 85" is sprayed to both the leading end surface 161a" and the outer surrounding surface 161b" of the insert portion 161" to clean these portions.
Under the connected condition between the first coupling 51" and the second coupling 52" as shown in FIG. 12(b), both the sealing contact portions 89", 189" are brought into contact with each other so as to seal between both the connection surfaces of the connecting receive mouth 61" and of the connecting insert portion 161".
Further, the aforementioned second conventional embodiment is also provided with ejection holes 85a" opened in the inner surrounding surface 61b" of the receive mouth 61" at the inmost portion as a variant of the ejection hole 85" for ejecting the cleaning fluid F as shown by the alternate long and two short dashes line in FIG. 12(a).
There are, however, the following problems (1) and (2) associated with the second conventional embodiment in addition to such a problem that a spill quantity of liquid from the first coupling 51" is large at the time of disconnection between both the couplings 51", 52" because a large liquid pool is provided in the inmost portion of the connecting receive mouth 61" behind the sealing contact portion 89" when both the couplings 51", 52" are disconnected.
(1) In the case of the ejection hole 85" (refer to the one shown by the solid line in FIG. 12(a)):
At the time of disconnecting manipulation of the quick-acting coupling 26", foreign substances attached to both the leading end surface 161a" and the outer surrounding surface 161b" of the connecting insert portion 161" of the second coupling 52" can be preferably removed therefrom 161a", 161b" by spraying the cleaning fluid F thereto 161a", 161b".
But, is impossible to spray the cleaning fluid F to the inner surrounding surface 61b" and to the inmost end surface 61a" of the first coupling 51". Therefore, the foreign substances attached thereto 61a", 61b" are bitten between both the connecting surfaces of the sealing contact portion 89", 189" to cause damages thereof and/or enter the flow passage 60" on the first coupling side or the flow passage 160" on the second coupling side.
(2) In the case of the ejection hole 85a" (refer to the one shown by the alternate long and two short dashes line in FIG. 12(a)):
In this case, though it is possible to make the cleaning fluid F pass through the connecting receive mouth 61", it is impossible to spray the fluid F to the inmost end surface 61a" and it is also impossible to spray the fluid F strongly to the inner surrounding surface 61b".
Further, when the connecting insert portion 161" is started to fit into the connecting receive mouth 61", since the receive mouth 61" is closed and subsequently the flowing of the cleaning fluid F is stopped, it becomes impossible to clean the outer surrounding surface 161b" of the connecting insert portion 161".